An RFID system for a plurality of wireless tags (1) that move in a same direction is described. The system includes a first reader/writer (42D) that receives identification information of the wireless tags (A1,A2,A3,A4) from a first group of the wireless tags that are positioned at regular intervals, and writes and reads information to and from the first group of the wireless tags based on the identification information, and a second reader/writer (41E) that receives the identification information from a second group of the wireless tags (B1,B2,B3) each of which is positioned between every two adjacent wireless tags belonging to the first group, and writes and reads information to and from the second group of the wireless tags when the first reader/writer writes and reads information to and from the first group of the wireless tags.